The Charles Stark Draper Laboratory, Inc.

Richard K Araujo

John M Dahlen

James R Scholten

Matti Soikkeli

Narender K Chhabra

Robert W Reid

A low-cost floating drifter adapted to accurately follow near-surface ocean currents and transmit periodically to monitoring satellites data and position-determining information. Global tracking of ocean currents is made economically and scientifically feasible by the use of large numbers of such drifters. The drifter includes a floating surface buoy in the approximate shape of an oblate spheroid and containing an electronic system, a slotted plane antenna, transmitter, sunrise and sunset detector, environmental sensors, buoy hull strain sensor and battery power supply. The surface buoy is stabilized and induced to follow ocean currents by a drogue suspended from the bottom center surface. The drogue includes a wire-cored buoyant rope of up to hundreds of meters in length and weighted to a slight negative buoyancy. The drogue may also include an elongated cylindrical sock of substantially greater diameter than the rope. By means of the sunrise and sunset detector and the electronic system, the transmitter is controlled to operate only during selected passes of a solar synchronous satellite so as to conserve the battery and permit unattended life of up to several years. By means of the hull strain sensor and the electronic system the transmitted signal contains data from which the drogue integrity can be determined. Other status and environmental data are also transmitted. The drifter has special provisions to resist corrosion, fish-bite damage and biological fouling.

Low cost drifter

A two-axis quartz fiber passive tilt meter which includes housing and a quartz fiber suspended from the housing for conducting radiation and emitting the radiation from a distal end thereof. A pendulous mass is suspended from the quartz fiber and a damping fluid in the housing surrounds the quartz fiber and the mass. A detector senses the position of the spot of radiation emitted from the quartz fiber.

Growing community of inventors

Tewksbury, MA, United States of America

Richard K Araujo